ΔE 7.5, close: similar, with a visible difference side by side. Flanker Light Blue is a little lighter, cooler than Gray FS16440.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Flanker Light Blue is a little lighter, cooler than Gray FS16440.
The same difference applies the other way round: Gray FS16440 is a little darker, warmer.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Gray FS16440 on the colour wheel See Flanker Light Blue on the colour wheel
All matches: Gray FS16440 equivalents · Flanker Light Blue equivalents